Thermal cycling tests on uranium have shown that the dimensional changes that occur on cycling in the alpha range are directly related to both the texture of the material and its grain size: cold rolled rods generally elongate in the direction of rolling, while the same rods, after a beta-treatment, grow at rates several orders of magnitude lower. This considerable improvement by beta-treatment has been attributed to the texture randomization accompanying the heat-treatment. In the course of this heat-treatment, however, considerable grain growth occurs, which ahs the effect of causing surface roughening on cycling (also referred to as "bumping"); fine grained material generally retains a smooth surface. These observations led to the speculation that the most desirable structure in uranium, from standpoint of dimensional stability, is one that combines both a random texture and a fine grain size. Heat treatment of rolled rod offered no easy method to obtain such a product; powder metallurgical techniques, however, appeared ideally suited for the purpose. To this end, early in 1949, the Sylvania Electric Products Company initiated a program to develop suitable techniques for producing uranium powder compacts having the above-mentioned desired characteristics. Because of the availability of thermal cycling equipment at Argonne, …

Physics calculations have been made for various combinations of the four types of fuel assemblies to be used in the EBWR core. Two thicknesses of plates, 0.205 in. and 0.274 in., including the two 0.020-in. cladding layers, are to be made of both natural U and U containing 1.44% U235. A total of 148 assemblies, 74 natural and 74 enriched, are to be fabricated with six identical plates each. Various configurations of these fuel assemblies will be used to (1) change the critical size of the core, (2) change the power distribution in the core, and (3) change the amount of reactivity corresponding to a given stream volume in the core. The physics calculations show that uncertainties in critical mass are adequately covered by the number and variety of fuel assemblies and that the possible changes in core characteristics with the different fuel assemblies should provide valuable information about the factors affecting maximum power density and stability in a boiling water reactor.

Report issued by the Argonne National Laboratory discussing progress made by the Reactor Development Program during May 1966. Reactor physics, experiments, and safety studies are presented. This report includes tables, and illustrations.

This quarterly report discusses ongoing research and experiments at Oak Ridge National Laboratory in the Metallurgy Division. This report discusses water cooled reactors, liquid metal cooled reactors, reactor development metallurgy, basic metallurgy, applied metallurgy, and aqueous corrosion,